Current-controlling device.



L. BRADLEY.

CURRENT CONTROLLING vDEVICE.

APPLICATION I'ILED JAN. 8, 1912.

Patented Aug. 26, 1913.

2 SHEETFkSHEET 1 L.BRADLEY.

CURRENT CONTROLLING DEVICL. APPLICATION FILED JANIB, 1912.

Ptented Aug. 26, 1913.

2 SHEETS-SHEET 2.

PATENT-OFFICE.

LYNDE BRADLEY, OF MILWAUKEE, WISCONSIN.

' GURRENT GONTROLLING DEVICE.

Appnamn an January 8, 1912. Serial No. 569,950.

To all whom it may concern 7 Be it known that I, LYNDE BRADLEY, a citizen of the United States, residing at Milwaukee, county of Milwaukee, and State of Wisconsin, have invented new and useful Improvements in Current- Controlling Devices, of which the following is a specification. I

My invention relates to improvements in current controlling devices of the general type shown and described in former patent numbered 821697, and dated May 29th,

1906. v w I y The object of my invention is to improve mechanism of the general type set forth in said former patent, by providing means for varying the resistance substantially in direct proportion to the desired rate of current in crease, notwithstanding the fact that the rate of movement of the actuating member or lever may be uniform, while the rate of pressure increase is continuously accelerated. Also to provide for a continued movement of the actuating member or lever to short circuit or out out the resistance columns after a desired minimum resistance has been attained, without varying, or at least without increasing the pressure upon the columns. i

My invention also involves the provision of means whereby interchangeable pressure varying members may be employed, and pressure and current increases provided for in any desired proportions, whether uniform or otherwise.

In the drawings Figure 1 is a rear elevation of a current controlling mechanism, with portions of the casing broken away to show the operating lever and pressure controlling cam. Fig. 2 is a detail side view, showing a portion of the controlling lever and carrier post, the lifting cam being shown in vertical section. Fig. 5 is a detail view showing a modified form of cam. Fig. 4 is a rear elevation of a modified form of construction, with parts broken away subpressed betweenthe carrier and the abutments. An operating lever 5 is pivoted to the casing at 6'. It is provided with brushes 7 and 8, adapted to move respectively over the sets of contact plates 9 and 10, (or 11 and 12) and 13 and 14, (01 Hand 16). All of these parts, together with neutral plate 17, the segment 18 and spring actuated equalizing roller 19, may be quite similar to those shown and described in my former patent, and therefore need not be here described with particularity. To actuate the carrier, however, I provide means which are radically different from what is shown and described in said former patent. I have provided the lever 5 with a cam 20, which, in Figs. 1 and 2, comprises a substantially oval shaped member having an opening therein, and an interior cam margin from which the carrier 2 is supported by a sleeve post 25 and roller 26, the latter being located within the cam member and resting upon said interior margin. Roller 26 is mounted upon a stud 27 projecting from post 25, as clearly shown in Fig. 2. Rod 28 serves as a guide for post 25.

With the parts in the position shown in Fig. 1, if lever 5 is swung to the right, the portion A of the cam margin will pass underneath roller 26 and lift carrier 2 progressively. The curvature of the margin A of the cam determines the degree of compression secured in any given stage of lever movement, and it is therefore possible to increase the compression in the desired proportion to lever movement at any part of the stroke, and to regulate the volume of current delivered to the motor accordingly. For some purposes, it is regarded as more desirable that the increase in current volume should be approximately constant, than it is that the eifort of the operator should be uniform, and in such cases, I therefore prefer to use a cam in which the outer portion of the cam margin A has a greater degree of curvature than the other portions.

columns is rapidly reduced during the first stages of the compression, while a very high degree of compression is required during the This is. done for the reason that the resistance of the Specification of Letters Patent. P t nted Aug. 26,1913,

final stages in order to reduce the resistance to a minimum. It would be theoretically possible to move the lever more rapidly, and through a considerable are, to secure this final compression in a given interval of time, but in practice, the tendency to move the with a segmental cam 20*.

operating lever either with a uniform speed, or more rapidly when the pressure is at a minimum. I therefore prefer to form the cam margin A with an abrupt curve at its outer end, as shown, and thus secure a high final compression with a small arc of lever movement.

The portion B of the cam margin is concentric with the fulcrum 6 of lever 5, and when this portion of the cam reaches the roller it may pass under it without lifting the carrier and therefore without increasing the pressure upon the resistance columns. While the lever is in this position, with cam portion B [in registry with roller 26, the rush 7 registers with contact plate 10 and cuts out or short-'circuits the resistance columns as described in said former patent. It will be observed that the left hand side of the cam has the same form as that above described-and as shown on the right hand side, but reversed in position. Like results in the increase of pressure upon the columns may therefore be secured when lever 5 is moved to the left.

Referring to Fig. 4, it will be observed that an operating lever 5" is employed for the same general purposes as the lever 5 in Figs. 1 and 2, but it is fulcrumed at 6 near the bottom of the casing and is provided The carrier 2 is provided with a sleeve post-25 and roller 26", similar in construction to the post 25 and 26 in Figs. 1 and 2. When this lever 5* is moved to the right, cam face a-m also moves to the right under the roller 26 and lifts the carrier until the cam face b-m passes underneath the roller, whereupon there will be no further increase in pressure, since cam face Z2m is curved in an are concentric with the axis of fulcrum pin 6.

' From a comparison of this view with Fig. 1,

the post, or whether it will be apparent that no specific form or arrangement of the cam 1s essential, except that the cam surface be formed to secure the desired graduated increase of pressure upon the'columns when the cam and roller have relative movement, followed by the desired conditions of pressure during the cutting out or short circuiting interval. It is, of course, not material whether the cam be mounted upon the lever and the roller upon the position of these parts on the respective supports be reversed.

The specific cam illustrated in Fig. 3 may be used interchangeably with the cam 20 in the structure illustrated in Fig. 1. It is designed to provide step by step current in creases. The marginal portion A of this cam, on either side of the center, may pass undenrollerQG in substantially the manneni'ttliat the marginal portion A of cam 20' passes under such roller, the carrier being simllarly lifted 1n each case, but with the cam 20, shown in Fig. 3, the cam margin A. is shorter and terminates at D, at which point it meets a difierently curved section E extending from the point D to the point F, where it connects with a relatively straight section B corresponding with the section or portion B illustrated in Fig. 1.

The curved portion or section E of the cam margin may provide for a slight reduction in pressure upon the columns by allowing the carrier to move downwardly to some extent after the point D on the cam passes under the roller 26. The cam illustrated in Fig. 3 is adapted to permit such a drop, as will appear from the divergence of the cam margin E from the dotted line G, said line G indicating an are described from the axis of pivot ('3 at the radius of the point D. From a comparison of the dotted line G with the margin IE, it will appear that the outer 'portion of the margin E is curved to provide an increasing pressure upon the columns, the carrier 2 being lifted to even a higher point than it occupies when the point D passes underneath the roller 26. When the point- F on the cam reaches roller 26, the maximum pressure is attained. The section B of the cam margin then passes underneath the roller 26 without increasing the pressure upon the columns and the brush 7 registers with the cut out contact plate 10 (or 12). The cam 20 is illustrated to-show that by employing a cam to transmit motion from the lever to the carrier, I am enabled to produce any desired re s1stance change, the only requirement being that the cam margin be shaped to produce the required rate of pressure increase. The increase of pressure 1s secured in each case by curving the cam margin to progressively shorten the radial distance from the axisof the pivot 6 and a reduction in pressure is secured by curving the cam margin to progres-v sively increase its radial distance from such pivot axis.

I claim 1. A current controlling device, comprising a variable resistance member, a pressure applying cam member, a member having relative travel along the cam face, a lever for effecting said relative travel, and means for applying the motion of one of said members to the resistance member, said cam face having a varying curvature.

2. A current controlling device, comprising a. variable resistance column, a pressure applying cam member, aroller adapted for relative travel along the cam face, a lever for effecting said relative travel, a pressure applying member. for said column, and a supporting connection between the pressure applying member and roller, said cam face being eccentrically curved along a line which progressively deflects from an are projected from its central portion.

3. A current controlling device, comprising a carrier, a set of variable resistance columns mounted thereon, a roller supported from the carrier, a circuit controlling lever, and a pressure applying cam adapted to transmit motion from said lever to the roller. 1

4. A current controlling device, comprising a. carrier, a set of variable resistance columns mounted thereon, a roller supported from the carrier, a circuit controlling lever, and a pressure applying cam adapted to transmit motion from said lever to the roller, said cam being provided with a face to receive said roller, curved to secure a substantially constant reduction in the electrical resistance of the columns, with a uniform rate of lever movement. i

5. A current controlling device, comprising a carrier, a set ofvariable resistance columns mounted thereon, a roller supported from the carrier, a circuit controlling lever, and apressure applying cam adapted to transmit motion from said lever to the roller, saidcam being provided with a face to receive said roller, curved to secure a substantially constant reductionin the electrical resistance of the columns, with a uniform rate of lever movement, and the end portions of said cam being formed to permit a continued movement of the lever after maximum pressure upon the columns is attained.

6. A current controlling device, comprising a carrier, a set of variable resistance columns mounted thereon, a roller supported from the carrier, a circuit controlling lever, and a pressure applying cam adapted to transmit motion from said lever to the roller, said cam being provided with a face to receive said roller, curved to secure a gradually'increasing current delivery with uniform lever movement, and the end portions of said cam being formed to permit a degree of lever movement with uniform pressure upon said columns, said lever being adapted to maintain said columns in an electrical circuit during the period of pres- ,sure increase, and cut them out of said circuit during the period of uniform pressure thereof.

7. In an electric current controller, the combination ofa variable resistance medium operative to vary electrical resistance under varying pressures, and a movable member adapted when actuated to vary the degree of compressing movement by in creasing it in the direction of its final stage, to progresslvely vary the electrical resist,

ance of said medium, substantially in direct cuiting said resistance medium, and a pressure varying member, adapted to maintain a substantially constant pressure upon the resistance medium during the short circuiting movement of the actuating member.

9. In an electric current controller, the

combination of a resistance medium, a device for subjecting said medium to pressure, and an actuating means for said pressure device, said actuating means and pres sure device being adapted to vary the pressure upon said resistance medium at desired stages of the actuating movement and to maintain the pressure unchanged at other stages of such movement.

10. In an electric current controller, the combination of an electrical resistance medium, the resistance of which is varied by pressure, a device for subjecting said medium to pressure, an actuating means for said pressure device, and a means of shortcircuiting or shunting the resistance medium from the circuit at a certain stage of the pressure; said actuating means and pressure device being arranged to maintain a substantially uniform pressure upon the resistance medium during the. final movement of the actuating means and while the resistance medium is being shortcircuited or shunted from the circuit.

11. In an electrical current controller, the combination of a variable resistance medium operative to vary the electrical resistance under varying pressures, and a movable member adapted, when actuated, to increase or decrease, and maintain the pressure at different stages of a continuous movement thereof.

In testimony whereof I affix my signature in the presence of two Witnesses.

LYNDE BRADLEY.

\Vitnesses Luvuun'ur (7. WHEELER, l. I). Bmmuu. 

